X-ray tube



Feb. 16 1926.

c. c. lAN VOORHIS X-RAY TUBE Filed Jan. 5, 1921 INVENTOR Cletus C fiirzl aaffizli .WITNESSES: vs/=7.

ATTORNEY Patented Feb. 16, 1926.

UNITED STATES 1,573,105 PATENT OFFICE.

GLETUS C. VAN VOORHIS, OF WILKINSBURG, PENNSYLVANIA, .ASSIGNOR TO WESTING- HOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

X-RAY- TUBE.

Application filed January To all whom it may concern:

Be it known that I. CLE'r s C. VAN Voonms. a citizen of the United States, and a resident of iVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in X-Ray Tubes, of which the following is a specification.

My invention relates to electrical discharge tubes of the vacuum type and more particularly to a method and apparatus for regulating the gas pressure in X-ray tubes.

()no object of my invention is to provide means for so controlling the gas in an electrical discharge device that the hardness of the tube or the penetrating power of the rays generated therein maybe controlled.

Another object of my invention is to provide means whereby gas may be readily dili'used through the glass envelope of an X-ray tube by the application of heat.

A further object of my invention is to provide a device of the above indicated character that shall be simple and inexpensive to construct and efiective in its operation.

In X-ray tubes, as heretofore constructed, it has been found that, when the tube is of the character employing a rare gas. such as helium or neon, the tube becomes aged after several months use, and the penetrating power of the X-rays is changed, thus increasing the difficulty of causing current to traverse the same. Some means is necessary to control the gas contents of the X-ray tube in order to restore the proper penetrating power of the same or, in other words, to change the hardness of the tube.

1 have found that helium will dilfuse through what are known as hard glasses, which have a high percentage of silica and boric oxide in their composition. It is my belief that glasses which are high in the boric oxide and silica content permit more readily the difl'usibility of gases therethrough. I utilize this principle in carrying out my invention in which I provide an extension to an X-ray tube and dispose a receptacle therearound containing helium or other desired rare gas. A heating winding is disposed around that portion of the tube that is surrounded by the receptacle for the purpose of so heating that portion of the tube as to permit the gas to diffuse from the receptacle into the tube. It has been found that helium will diffuse in this manner from the receptacle into the tube when the glass envelope is heated to a value relatively less than the softening point of the glass. If it is desired to cause the helium 1n the X-ray tube to be diffused into the air, a similar projection may be heated without the use of the gas-filled enclosing receptacle.

The single figure of the accompanying drawings is a view of an X-ray tube embodying my invention.

An X.-ray tube. 1 comprises a glass bulb or receptacle 2, a cathode 3, an anode or target 4 and means 5 and 6 for controlling the amount of gas in the envelope of the tube.

The receptacle or envelope 2 is provided with tips or portions 7 and 8 around which I are disposed heating windings 9 and 10, respectively. A. receptacle 11 is disposed around the portion 8 and the winding 10 and is adapted to contain a quantity of rare gas, such as helium or neon. Under normal conditions, the gas in the receptacle 11 does not communicate with the interior of the tube 2 and there is no mechanical opening between the portion 8 and the receptacle 11.

If it is desired to increase the quantity of rare gas in the tube 2, sufficient current 1s permitted to traverse the winding 10 to heat the portion 8 of the tube 2 to a point relatively lower than that of the temperature at which it softens.

I have found that, under this temperature condition, the helium in the receptacle 11 will diffuse into the tube 2. I have also found that, if it is desired to expel some of the helium from the tube 2. it is only necessary to heat the portion 7 by causing sufficient current to traverse the winding 9 to heat the same to a point slightly lower than its softening point. This will cause the heliumto diffuse through the portion 7 into teristics that they may be attached to, a lampplug in a commercial lighting circuit for restoring the gas to the tube or to remove gas therefrom.

My invention is not limited to the specific X-ray tube illustrated, as it may be applied to other partial vacuum'devices and it may be variously modified without departing from the spirit and scope of the invention, as set forth in the appended claims.

I claim as my invention 1. The method of regulating the vacuum of a glass vacuum tube, which consists in introducing a gas into said tube by applying a gas to the surface of said tube and heating said surface.

2. The method of regulating the vacuum of a glass vacuum tube, which consists in introducing a gas into said tube by applying the gas to the surface of said tube and heating said surface to a degree less than the softening point of the glass.

3. The method of regulating the pressure in a vacuum tube having an envelope, a part of which at least is formed of hard glass, which consists in difl'using through said hard glass :1 gas which is in contact therewith by heating said hard glass.

'4. The method of regulating the pressure in an X-ray tube having a part at least formed of hard glass which consists in diffusing a rare gas through said hard glass by heating the latter to a degree less than the softening oint thereof.

5. The com hination with a glass receptacle, of a gas-enclosing receptacle surrounding a portion of the glass receptacle, and means for heatingthat portion of the glass receptacle.

6. The combination with a glass receptacle, of a gas-enclosing receptacle surrounding a portion of the glass receptacle, and electrical means for heating that portion of the glass receptacle. 1

7. The combination with .a glass receptacle, of a gas-enclosing receptacle surrounding a portion of the glass receptacle, and electrical means for heating that portion of the glass receptacle to a temperature relatively less than the softening temperature of the glass.

8. The combination with a glass receptacle, of a helium-enclosing receptacle surrounding a portion of the glass receptacle, and a heating winding surrounding that portion of the glass receptacle whereby the helium is diffused into the glass receptacle cember 1920.

when the same is heated to a predetermined temperature.

9. The combination with a glass receptacle containing a gas, of means for so heating a [portion of the receptacle that the gaseous content of the receptacle maybe controlled by a condition exterior of said receptacle. I i 10. The combination with a glass receptacle containing a quantity of helium, of means for so heating a portion of there ceptacle that the helium may be difi'used through the glass to control the gaseous contents of the receptacle, whereby the pressure within said receptacle may be regulated.

11. The combination with a glass receptacle containing a quantity of helium, of electrical meansfor so heating a portion of the receptacle as to control the diffusion of the helium through the glass, whereby the prtessure within said receptacle may be regu- 12. The "combination with a vitreous X- ray bulb, of means for heating a portion of the bulb to control the diffusion of the gas in the bulb, whereby the degree of vacuum within said bulb may be regulated.

13. The combination with an X-ray bulb, of a receptacle enclosing a portion of the bulb, helium within the bulb and within the receptacle, and means for so heating the enclosed portion of the bulb that the admission of helium to the bulb may be controlled.

14. The combination with a vitreous electriealdischarge tube, of means for increasing and decreasing the gaseous content of said tube through said Vitreous material in a predetermined amount.

15. The combination with an electrical discharge device composed of a vitreous material having a rare gas therein, of means for increasing or decreasing the amount of gas within said device by osmotic action through said vitreous material.

16. The combination with an electrical discharge device composed in part of glass and having a rare gas therein, of means for increasing or decreasing the amount of gas within said device in a predetermined amount by diffusion through said glass.

In testimony whereof, I have hereunto subscribed my name this 30th day of De- CLETUS C. VAN VOORHIS. 

